After initial reports Thursday evening that the wreckage of the plane had been been found, EgyptAir subsequently said they were mistaken, and that the debris has not been located.

Then, on Friday morning, the Egyptian military said it had located personal belongings and debris which it said were from the missing plane.

The search team found body parts, luggage and other debris in the crash area, which is roughly 180 miles north of Alexandria.

And the European Space Agency said on Friday afternoon it had spotted an oil slick near the wreckage site which could offer clues as to whether the plane broke up in the air or on impact with the sea.

It also emerged on Friday that the passenger manifest did not contain any names that were on terror watch lists, though investigators have not ruled out terrorism as a motive.

President Abdel Fattah al-Sisi has confirmed there is no hope of any survivors after his office issued a statement saying: "The presidency with utmost sadness and regret mourns the victims on aboard the EgyptAir flight who were killed after the plane crashed in the Mediterranean on its way back to Cairo from Paris."

Another of the victims has been identified as Mervat Zakaria, leader of the cabin crew. She had a brief experience as an actress in 1985 before she joined EgyptAir to work as flight attendant, quitting her short career in drama. She participated with a small role in 1985 in a famous soap opera called The Journey of Mr. Abo el-Ella al-Bershery.

What we know about the journey of MS804

It was 10 miles into Egyptian airspace when it disappeared at around 2:30 am Egypt time (1:30am BST), flying in clear skies.

Greek authorities have said it then fell 22,000 feet and "swerved sharply" in Egyptian airspace. "The plane carried out a 90-degree turn to the left and a 360-degree turn to the right, falling from 37,000 to 15,000 feet and the signal was lost at around 10,000 feet," defence minister Panos Kammenos said.

The Airbus A320 was built in 2003 and was on its fifth journey of the day. It had clocked 48,000 flight hours. The captain has 6,275 flying hours, including 2,101 on the A320, EgyptAir said. The co-pilot has 2,766.

What caused EgyptAir flight MS804 to crash?

So far no cause has been established, but aviation experts have suggested the crash could have been the result of terrorism. Here, we examine the theories that have been put forward so far.

Mechanical malfunction

"A major technical fault - the explosion of a motor, for instance - seems improbable," said aeronautics expert Gerard Feldzer, underlining that the A320 in question was "relatively new", having entered service in 2003. "In addition, the A320 has an excellent safety record as the best-selling, medium-range airliner in the world. An A320 takes off or lands every 30 seconds around the world."

As the plane set off from France, the doomed Airbus A320 was on its fifth journey in 24 hours. The 13-year-old airliner had taken in stops as far afield as Eritrea, Egypt and Tunisia before its final flight - with no reported sign of mechanical malfunction.

"It's a modern plane, the incident happened in mid-flight in extremely stable conditions. The quality of the maintenance and the quality of the plane are not in question in this incident," Jean-Paul Troadec, former director of France's aviation Bureau of Investigation and Analysis, told Europe 1 radio. Egyptair "is a company with authorisation to operate in Europe, so it is not on any blacklist," he added.

The "fall rate" of the AirEgypt plane will provide crucial information on the likely cause of the crash, a French airline pilot has said. "The quantity of meters that the plane loses per minute can say a lot," said pilot Francois Suchel. "Engine failure would show a relatively low fall rate. Depressuration would show a much higher fall rate of around 5,-6,000 feet per minute."

David Learmount, operations and safety editor at Flight Magazine, said the Greek defence ministry's announcement that the plane fell 22,000 feet and swerved sharply in Egyptian airspace before it disappeared from radar screens suggested that "the flight had clearly been destabilised, but the cause of the destabilisation is not known". He said it was hard to say whether this meant the plane was making evasive action or was out of control, however it didn't necessarily mean that there had been an explosion on board.

Shot down

It was also unlikely the plane was shot down, experts said, as the region is one of the most monitored in the world and it would be hard to conceal such an attack.

"The first thing to do is to recover debris that will give us some indications on the accident... to see if there are any traces of explosives," aeronautics expert Gerard Feldzer said.

Explosion

Prosecutors in Paris have launched an investigation into airport workers at Charle de Gaulle airport amid fears flight MS804 was attacked by terrorists.

There have been no confirmed reports yet of any terror group claiming responsibility for bringing down the plane. That includes Islamic State of Iraq and the Levant (Isil), which has put out other propaganda material but nothing thus far on the EgyptAir disaster.

EgyptAir says that security scans on the aircraft took place prior to take-off from Paris. All employees of the airport and airline that could have had access to the plane or luggage prior to take-off are reportedly being questioned.

Tory former minister Sir Gerald Howarth has questioned whether the incident could be linked to the fact that several airport workers in Paris had their authorisation revoked in December due to their links with Islamic extremism.

In a live interview with CNN, Hillary Clinton said: "It does appear that it was an act of terrorism. Exactly how, of course, is yet to be determined."

Donald Trump posted the following message on Twitter: "Looks like yet another terrorist attack. Airplane departed from Paris. When will we get tough, smart and vigilant? Great hate and sickness!"

Egypt's aviation minister Sherif Fathy said: “If you analyse the situation properly the possibility of having a terror attack is higher than the possibility of having a technical [problem]”.

Alexander Bortnikov, head of the Russian Federal Security Service, said he believed the plane was downed by terrorists "in all likelihood".

FBI Director James Comey has said that there is no evidence that flight MS804 was brought down intentionally, and that no group had claimed responsibility.

Smoke in the cabin?

Smoke was detected inside the aircraft cabin in the final moments before it crashed, according to the Aviation Herald, a specialist site that reports on the airline industry.

It was not clear exactly what the detected smoke means but it could indicate an explosion or a fire on board the aircraft.

The Herald said on Friday night that three independent sources passed on data from the A320's Aircraft Communications Addressing and Reporting System (ACARS). The system shows that at 2.26am local time smoke was detected in aircraft lavatory.

A minute later another smoke sensor went off. A series of faults continued until 2.29am when the system stopped recording.

Submarine deployed to find black box

Egypt has deployed a remote-controlled submarine to try to find the airliner’s black boxes to determine whether it was technical failure or terrorism that caused the A320 to plunge into the sea on Thursday.

The submarine can reach depths of 9,800 feet but parts of the Mediterranean are even deeper. It is not clear that the submarine could recover the black box recorders even if it locates them.

Moreover, the Egyptian government has admitted that the submarine might be unable to operate at extreme depths.

"No plans" to further tighten security

The Paris airports authority said it has no plans to tighten security further after the EgyptAir crash but airport workers expressed concern on Sunday about weak spots in the systems.

Pauline Godebout, an airline desk officer, said there were "sometimes" identity checks at entrances to terminals at Charles de Gaulle airport.

“But they don't do it all the time. I think it’s a budget issue. It’s expensive and there are so many doors to the airport that it's very difficult to secure them all.”

An airports authority spokesman told the Telegraph that security had already been stepped up after recent terrorist attacks.

EgyptAir's troubled history

Since it was founded in 1971, EgyptAir has been dogged by devastating crashes and hijackings.

The deadliest came in 1999 when EgyptAir flight 990 plunged into the Atlantic Ocean near the island of Nantucket in Massachusetts, killing all 217 people aboard. An investigation found the crash was probably caused deliberately by the co-pilot. A cockpit recording captured him muttering “I rely on God, I rely on God,” over and over as the plane slammed into the ocean. Egypt’s government to this day disputes that the plane was crashed deliberately.

The Egypt national airline suffered three deadly crashes in its 45 years of existence. A crash landing in Yemen in 1972 killed 42 people while another 37 were killed the following year in Cyprus.

On Christmas Day 1976 an EgyptAir Boeing 707 slammed into a factory in Thailand, killing all 52 people aboard and another 19 on the ground. Investigators blamed pilot error but Egypt accused the Thai control tower of failing to warn the crew of bad weather.

The most recent crash before the disappearance of MS804 was in EgyptAir 843, which hit a hill as it came in to land in Tunisia in 2002. 14 people of the 62 aboard were killed.

EgyptAir has also suffered a string of hijackings from its earliest years to the present day.

No one was killed in the first hijacking in 1976.

But things turned bloody a decade later when Palestinian gunman took over a flight returning from Athens to Cairo. The flight was forced to land in Malta where a tense standoff took place. Then Egyptian commandos launched an botched raid on the aircraft, which ended with the deaths of 58 passengers.